Estudo de aproveitamento econômico das lamas de uma mineração de ferro, através de concentração por flotação catiônica reversa

Abstract

High grade deposits were mined in the early stages of the activity. No attention was paid to maximizing the use of the deposits. Even nowadays, millions of tons of useful minerals are disposed every year into tailings ponds.This study investigated the possibility of economically retrieving ultrafine tailings (slimes) from an iron ore concentrator via reverse cationic flotation. Following size analysis, chemical, and mineralogical characterization, desliming and flotation tests were performed with the slimes aiming at verifying the floatability of the material. The traditional approach suggests that ultrafine particles do not float. Different dosages of collector and depressant were used.The promising results of the bench scale tests lead to carrying out pilot scale tests with both, the currently produced slimes, and the slimes that will be generated in the future, after the commissioning of the mining companys expansion project.It was observed that a reverse cationic column flotation process, using high depressant dosage, was selective, yielding high grade concentrates with low impurities contents at high levels of iron recovery, approximately 60% mass recovery and 80% metallic recovery in the flotation stage, excellent concentrate grades (less than 1% silica) and tailings grades (approximately 12% iron), and also high selectivity levels. The overall mass recovery reached 20%. Considering that the generation of slimes after comissioning the Expansion Project will be 970t/h, it is estimated the production of an extra amount of around 1,400,000t per year of ultrafine concentrate, adding a significant financial profit to the mining company. The conclusion was that ultrafine materials do float, if processed separately. The ultrafines flotation is an economic alternative for increasing the recovery in mineral processing operations. The flotation of ultrafines may also be evaluated for decreasing or treating effluents disposed to the environment, irrespective of heir source, mineral, biological, organic or radioactive.